419P Transanal endoscopic microsurgery for local regrowth after curative radio-chemotherapy for rectal cancer

Abstract

Low rectal cancer staged as T2-T3 N0-N1 is currently offered abdominoperineal resection (APR) as a standard treatment, but with a significant risk of sequalae due to the extensive surgical procedure. An alternative to upfront surgery is curatively intended radiotherapy and chemotherapy, followed by observation in cases with complete clinical response (cCR). Local regrowth during follow-up may be treated with transanal endoscopic microsurgery (TEM) and thus allowing an organ sparing option compared to extirpation. We wanted to describe the results of TEM in patients with local regrowth after cCR to radio-chemotherapy. In a phase II trial, we included patients with histopathological verified adenocarcinoma of the rectum who fulfilled criteria for APR or ultralow resection based on having a primary resectable T1-T3 N0-1 Mo category. All patients underwent 50.4 Gy/28 fractions to elective lymph node regions and 62 Gy/28 fractions as a concomitant boost to the tumour volume. Concomitant capecitabine 825 mg/m2 x 2 was given on treatment days. In the intention to treat population of 107 patients (108 included and one withdrew before any procedures) 92 patients (86.0 %, 95% CI: 78– 92) had cCR and were allocated to observation. Of 23 patients with biopsy proven local regrowth, 7 patients were referred to TEM. There were no surgical complications according to Clavien-Dindo (zero for all patients). Within a median follow-up time after TEM of 18 months (range 1 – 43 months), only one patient developed liver metastasis 10 months after TEM. The treatment was well tolerated with a low LARS score. One patient had urge symptoms within the first 30 postoperative days and one patient had urge symptoms and a low grade of proctitis at 30 months follow-up. TEM is a minimal invasive treatment modality for local regrowth after curative highdose radio-chemotherapy. There were no surgical complications and patient reported only few adverse symptoms. The rate of rectal preservation after radio-chemotherapy can be increased without impairing oncological outcome and thus treating local regrowth with TEM could be a new standard for these patients.